Fix for xcb-proto-1.12 make check:

--- a/src/xcb.xsd
+++ b/src/xcb.xsd
@@ -44,6 +44,15 @@ authorization from the authors.
     <xsd:complexType>
       <xsd:attribute name="bytes" type="xsd:integer" use="optional" />
       <xsd:attribute name="align" type="xsd:integer" use="optional" />
+      <xsd:attribute name="serialize" type="xsd:boolean" use="optional" />
+    </xsd:complexType>
+  </xsd:element>
+
+  <!-- Alignment -->
+  <xsd:element name="required_start_align" >
+    <xsd:complexType>
+      <xsd:attribute name="align" type="xsd:integer" use="required" />
+      <xsd:attribute name="offset" type="xsd:integer" use="optional" />
     </xsd:complexType>
   </xsd:element>
 
@@ -76,14 +85,13 @@ authorization from the authors.
     <xsd:sequence>
       <!-- switch(expression) -->
       <xsd:group ref="expression" minOccurs="1" maxOccurs="1" />
+      <xsd:element ref="required_start_align" minOccurs="0" maxOccurs="1" />
       <xsd:choice>
         <!-- bitcase expression - bit test -->
         <xsd:element name="bitcase" type="caseexpr" minOccurs="0" maxOccurs="unbounded" />
         <!-- case expression - value test -->
         <xsd:element name="case" type="caseexpr" minOccurs="0" maxOccurs="unbounded" />
       </xsd:choice>
-      <!-- default: -->
-      <xsd:group ref="fields" minOccurs="0" maxOccurs="1" />
     </xsd:sequence>
     <xsd:attribute name="name" type="xsd:string" use="required" />
   </xsd:complexType>
@@ -201,6 +209,7 @@ authorization from the authors.
       <xsd:element ref="field" />
       <xsd:element ref="list" />
       <xsd:element ref="fd" />
+      <xsd:element ref="required_start_align" />
     </xsd:choice>
   </xsd:group>